Pneumatic tire



`Iuly 18, 1939. E. wlTz-ENMANN en if Filed Nov. 26. 1938 Patented July 1s, 1939 UNITED STATES PATENT OFFICE Application November 26, 1938, Serial No. 242,613

In Germany January 27, 1938 4 Claims. (Cl. 152-157)l In connection with pneumatic tires, especially so-called high-pressure motor vehicle tires, dangerous defects` are often caused chiefly by foreign bodies (such as nails, pins, splinters of glass, and so forth). penetratingv the outer cover and making their way through the latter to the inner tube which they puncture so that the air contained under high pressure therein escapes through the wall of the outer cover, or at its l seating on the wheel rim. Another 4source of damage to pneumatic tires is the inevitable extensive heating of the structure of the tire occurring at high speeds or during a. prolonged run, especially under a'hot sun. This softens l5 the inner tube to some extent and tends to weaken it and may then'lead to the bursting of the tube and consequently to the destruction of the outer cover.

An object of the present invention is to minin mise these inconveniences Without notably increasing the weightof the tire or affecting its resilience.

Further objects of the invention are to substantially protect the inner tube-from the effects of undue absorption ofheat, ensure the maintenance of good resilience of the tire, enable the tire to be subjected to maximum stressing, and above all safeguard the tire from sudden collapse and the consequences of accident occasioned w thereby. With these objects in view thepresent invention provides a new and improved inflatable tire tube comprising an -annular body of vspongy rubber presenting intercommunicating cells open 35 to its interior and an integrally formed impervious outer skin produced by vulcanization,said cellsI being permeated-with compressed air on inflation of said tube, and said body, in the event of its impervious skin being punctured, forming- 40 an auxiliary cushion allowing the imprisonedair to escape only slowly. The accompanying drawing represents a typical embodiment ofA the invention, Fig. 1 being a` cross section of a complete tire, and Figs. 2

45 and 3 fragmentary cross' sections of the tire tube before and after ination.

a denotes the tire outer coverfb the dividedh wheel rim, and d an annular body of spongy 'rubber presenting a central annular passage e into' 50 `which compressed air is admitted, through a passage f, on the tire being inflated.

According to theinvention, the spongy rubber ly impervious to air, on the outer side, in a simple manner..

0n pumping up the tube c', d the cellular structure of the body d is uniformly permeated with compressed air since the individual cells g 5 (Fig. 2) bounded by the walls g and intercommunicating through the passages Ic are powerfully inflated (Fig. 3), so that the outer walling or sheathing c bears firmly against the inside of the outer cover a. 1

In the event of damage to the tire and consequently to the inner tube, the imprisoned compressed air escapes only at a slow rate and the contracting spon'gystructure under the slow collapsing ofthe individual Walls g of the cells g, l5

forms a resilientcushion which prevents sudden collapse and therefore partial-or complete destruction of the tire and the? occurrence of. accidents resulting therefrom.

It is also evident that the spongy-rubber structure affords-a kind of insulation against undueheating of the interior of the tire, since much of the air is uniformly distributed, in the form,

nular body of spongy rubber presentingl interl communicating cells open to its interior and an integrally formed impervious outer skin,v said cells being permeated with .compressed air on inflation of said tube, and said body in the event of its outer impervious skinbeing punctured forming an auxiliary cushion allowing the imprlsoned air to escape only slowly.

2. An inflatable tiretube vas claimed in -claim` 40- 1, wherein the said annular body has a central cavity of circular cross section.

3. An inflatable tire tube as claimed in claim. 1, wherein the said annular body has a central *cavity of circular cross section and an inwardly t5l directed radial passage in communicationtherewith.l

4:'. A pneumatic tire-comprising, in combina' tion, an outer cover, and an inner inflatable tube j composed of an annular body of spongy rubber 1 50 presenting intercommunicating cells open to its interior and of ari-'integrally formed impervious outer skin; 

